This invention relates to improved leak detection systems and, more particularly, to a leak detection system used with a fluid dispenser and pump and to a method for detecting leaks.
One particular application for the system and method of this invention is to detect leaks in a fluid delivery line through which fluid is intermittently delivered under pressure. For example, remote pumping systems are being used more frequently in gasoline service stations. Typically, a pump and motor unit is submerged in an underground tank and is used to supply gasoline to a plurality of dispensers. These systems conventionally include a pump, a dispenser, a conduit connecting the two, and a valve, such as a check valve, in the conduit isolating the pump from the dispenser when a fluid is not being dispensed. The fluid in the discharge line portion of the conduit between the check valve and the dispenser is under pressure during dispensing and between dispensing operations. When these remote pumping systems are used for the dispensing of gasoline, it is important to determine whether or not there is a leak in the conduit since continued undetected leakage over prolonged periods may result in a dangerous accumulation of gasoline in the ground. A leakage rate in excess of 3.5-4.0 gallons per day is considered intolerable and should be detected.
In order to determine whether or not a leak exists in the conduit, it is desirable that the valves at the ends of the conduit seal tight. If the valve at the dispenser end is defective, it will be readily observable since the fluid, such as gasoline, will be seen dripping from the dispenser nozzle. However, since the check valve is not readily observable, precautions should be taken to be sure that the check valve is properly seated to prevent flow of the fluid from the discharge line back through the check valve toward the pump. If such flow exists, it would render the leakage test inaccurate.
Accordingly, it is an objective of this invention to provide an improved leak detection system and method for detecting leaks in a delivery line portion of a conduit between a valve and a fluid dispenser.